• Limiting exposure in the beam to prevent disturbance to birds and aircraft. The latter would involve hazards due to incidental interference with electronic equipment or electro-explosive hazards; and • Limiting exposure of organisms on the ground in the region of the receiver and beyond to minimize local ecological effects due to selective elimination of some classes of animals. a. Organism Exposure Microwave energy received at the ground could conceivably be lethal to a limited size range o organisms. Depending on the location, these could include snakes, lizards, rodents, and somt insects. These organisms usually constitute the most significant members of the food chain including the major herbivores (rodents) and some important carnivores (snakes). If microwave energy at the anticipated levels does prove to be lethal to some organisms in the receiver area, ther the results could be felt over a wider region. The receiver area could act as a biological sink attracting in-migration of organisms replacing those killed inside the area. Alternatively, or in addition, this area could act as a source of other organisms which might reproduce rapidly if theii predators are reduced, and migrate out of the receiver region. Metal screening to attentuate microwave energy beneath the rectenna is recommended as an inexpensive precautionary measure which would prevent such effects. b. Human Exposure The potential hazard of human exposure to the microwave beam relates both to those persons occupied in maintaining and operating the receiving site and the space crew maintaining and operating the space transmitting station. In the Western World, for many years the accepted exposure standard for microwaves has been 10mW/cm2 (i.e., the maximum power density to be measured in space accessible to workers when measured in the absence of the workers). The existence of much lower permissible exposure levels (e.g., down to lOgW/cm2) in Eastern Europe for long-duration exposure will pose a potential problem in the planning of the satellite solar power system both on the ground and in space. Many Western scientists believe future research will verify the validity of the 10mW/cm2 exposure standard. Some Czech scientists believe that the 10gW/cm2 long duration standard could be safely raised. Leading Russ'an scientists believe in the validity of their standard. It is likely that the general public beyond a 15-km radius will be exposed to less than 10pW/cm2. This would seem acceptable even under Soviet or Czech standards, particularly since the microwave radiation will be cw and not pulsed. It is necessary to understand biological effects even at very low exposure levels. Programs to provide such understanding are being considered by the Office of Telecommunications Policy.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==